1. Field of the Invention
The present invention relates to a blind rivet and a drawing mandrel. The drawing mandrel has a mandrel head and a mandrel shaft, and the blind rivet has a cylindrical rivet shell surrounding the drawing mandrel for a portion of its length. The rivet shell has in its outer cylindrical surface at least one attenuation groove.
2. Description of the Related Art
A known blind rivet is disclosed in European Patent Application EP 0 168 355 A1, where several circumferential grooves or discontinuous recesses are provided in a tubular body 1 and are longitudinally located at some distance from each other. The use of these blind rivets is relatively flexible in that they may be used to connect two or more components of varying thickness. It is possible, within certain limitations, to rivet varying material thicknesses to each other, without the need to use a specially fitted blind rivet. However, there are difficulties with the "locking behavior" of this type of known rivet. Often the formation of the rivet head is not satisfactory and the rivet connection does not have the desired or necessary strength.
Another blind rivet is known from EP 0 277 759 B1, which also has a tubular shaft 11 that has zones of modified strength provided by circumferential grooves 27, 28 and 29. These grooves are produced by rolling, and during the rolling process the rivet shell is widened. Thus, the rivet shell does not sit tightly (i.e., with the necessary friction) on the drawing mandrel and therefore can move relative to the drawing mandrel. This makes it more difficult for a user to handle this type of blind rivet. Accordingly, the rivet shell, in many cases, must be properly positioned on the drawing mandrel before setting. Frequently, this rivet shell must be set several times with a rivet tool or setting tool, because the setting stroke is not adequate. This, of course, causes time loss in the setting process even though time saving was one of the purposes of using multiple range blind rivets in the first place.